dcm The .dcm extension files are raster image format files that are universally used by the medical community for creating and storing body scans of patients. This format was developed by NEMA (National Electrical Manufacturers Association) and is primarily associated with the DICOM (Digital Imaging and Communications in Medicine) image format files.
sgi A .sgi extension file saves images in the original Silicon Graphics Image format. These files are originated from the library of SGI images that were there on every Silicon Graphics machine. SGI files are also referred to as RGB, IRIS or Irix RGB., .sgi image files can be saved in 8-bit color, 16-bit or 32-bit color. GIMP has the compatibility to read and write .sgi extension files and also has a dialog box that pops up to help select the compression type. The preferred compression is RLE and while it reduces the file size, it is advisable to check once it is done to ensure that the file size is indeed reduced as sometimes the size is more than the actual file size.